Various prior art devices have been provided to modify the pickup box in order to reduce the aerodynamic drag of the vehicle.
One such aerodynamic drag reducer is the use of a tonneau cover connstructed of canvas, wood or metal panels which extend between the side walls of the truck box from the tailgate to the passenger cab to completely enclose the pickup box. In addition to reducing the aerodynamic drag, these tonneau covers are useful to conceal and protect tools or other cargo which may be carried in the truck.